Skip to main content

Invading Ants Go On Diet

Argentinian ants have successfully invaded California by being aggressive and flexible in their diets. Steve Mirsky explains, with reporting by Harvey Black.

Science, Quickly

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


If you’re an invading, meat-eating Argentinian ant, and you run out of prey, there’s only one thing to do if you want to keep invading—become a vegetarian. And that’s just what the carnivorous Argentinian ants that have invaded California did.  They switched and began to eat vegetable matter.  No, these two-millimeter long critters didn’t develop moral qualms about eating meat and they aren’t trying to save the planet.  They just ran out of their first choice, native ants.  Researchers writing in the Proceedings of the National Academy of Sciences say that these ants gobbled up the native ants, which can be ten times their size. The newcomers then had no choice but to carbo-load, switching over to such sweet treats as honeydew nectar produced by aphids. The ants, which are believed to have arrived in California on ships carrying coffee and sugar from Argentina in the 1890s, have caused problems for big creatures as well. The coastal horned lizard, which dined on domestic ants, has declined in numbers by about half recently.  Apparently because the lizard doesn’t particularly care for Argentinian food.

—Steve Mirsky, with reporting by Harvey Black 

Invading Ants Go On Diet